A male with unilateral microphthalmia reveals a role for TMX3 in eye development.

Anophthalmia and microphthalmia are important birth defects, but their pathogenesis remains incompletely understood. We studied a patient with severe unilateral microphthalmia who had a 2.7 Mb deletion at chromosome 18q22.1 that was inherited from his mother. In-situ hybridization showed that one of the deleted genes, TMX3, was expressed in the retinal neuroepithelium and lens epithelium in the developing murine eye. We re-sequenced TMX3 in 162 patients with anophthalmia or microphthalmia, and found two missense substitutions in unrelated patients: c.116G>A, predicting p.Arg39Gln, in a male with unilateral microphthalmia and retinal coloboma, and c.322G>A, predicting p.Asp108Asn, in a female with unilateral microphthalmia and severe micrognathia. We used two antisense morpholinos targeted against the zebrafish TMX3 orthologue, zgc:110025, to examine the effects of reduced gene expression in eye development. We noted that the morphant larvae resulting from both morpholinos had significantly smaller eye sizes and reduced labeling with islet-1 antibody directed against retinal ganglion cells at 2 days post fertilization. Co-injection of human wild type TMX3 mRNA rescued the small eye phenotype obtained with both morpholinos, whereas co-injection of human TMX3(p.Arg39Gln) mutant mRNA, analogous to the mutation in the patient with microphthalmia and coloboma, did not rescue the small eye phenotype. Our results show that haploinsufficiency for TMX3 results in a small eye phenotype and represents a novel genetic cause of microphthalmia and coloboma. Future experiments to determine if other thioredoxins are important in eye morphogenesis and to clarify the mechanism of function of TMX3 in eye development are warranted.

Codeine accumulation and elimination in larvae, pupae, and imago of the blowfly Lucilia sericata and effects on its development.

The aim of this study was to evaluate the reliability of insect larvae as samples for toxicological investigations. For this purpose, larvae of Lucilia sericata were reared on samples of minced pig liver treated with different concentrations of codeine: therapeutic, toxic, and potentially lethal doses. Codeine was detected in all tested larvae, confirming the reliability of these specimens for qualitative toxicology analysis. Furthermore, concentrations measured in larvae were correlated with levels in liver tissue. These observations bring new elements regarding the potential use of opiates concentrations in larvae for estimation of drug levels in human tissues. Morphine and norcodeine, two codeine metabolites, have been also detected at different concentrations depending on the concentration of codeine in pig liver and depending on the substance itself. The effects of codeine on the development of L. sericata were also investigated. Results showed that a 29-h interval bias on the evaluation of the larval stage duration calculated from the larvae weight has to be considered if codeine was present in the larvae substrate. Similarly, a 21-h interval bias on the total duration of development, from egg to imago, has to be considered if codeine was present in the larvae substrate.